To appreciate the difference, consider that the old way involves introducing DNA into mouse embryonic stem cells, and then selecting for the rare cells that take up and incorporate the DNA in the right way. Then the ES cells have to be injected into a blastocyst, followed by mouse breeding to “go germline.”

With CRISPR/Cas9, it’s possible to inject pieces of RNA that target the desired genetic changes, straight into a one-cell stage mouse embryo. Not every embryo has all the right changes, but the frequency is high enough to inject and screen. As this review explains, it’s possible to introduce mutations into three genes at once and get mice quickly, rather than make each one separately and then breed the mice together, which can take many months.

Also, because of the need for drug selection, the targeting construct in old-school gene targeting has to be a blunt instrument. That can make it hard to make subtle changes to a gene — like introduce point mutations corresponding to natural variations linked with human disease — without taking a sledgehammer to the entire gene locus. CRISPR/Cas9 takes care of that problem.

Despite the advantages of this technology, three things to keep in mind:

*Emory’s Mouse Core has been working with the company Ingenious Gene Targeting, and has been out-sourcing some of the tedious aspects of old-school gene targeting in mice to Ingenious, starting last year. Technicians there can generate a dazzling array of conditional knockouts. If you want your favorite gene to flip around and produce a fluorescent protein when you give the mice an antibiotic, but only in some cells — Ingenious can do that. Old school is actually still the way to go for fancy stuff like this.

Much of basic biomedical research concerns proteins. The enzymes that keep cells running, the regulators and receptors that control what our cells do, the antibodies that defend us against invaders — all of these are proteins.

That means every day, scientists are asking questions like:

What’s happening to my favorite protein? Is there more or less of it in this sample? What other proteins work with it or stick to it?

That’s where a proteomics core facility comes in. Given a mixture of hundreds or even thousands of proteins, proteomics specialists can separate, identify and quantify them.

There’s a scene in both the 1971 and 2005 film adaptations of Roald Dahl’s Charlie and the Chocolate Factory, in which a chocolate bar is separated into millions of tiny pieces and sent flying across a clean room. Protein mass spectrometry resembles the first part of this process. Read more